In recent years, there has been known a virtual machine system provided with a number of virtual machines for operating the operating systems individually, and a virtual machine control device for controlling the virtual machines. For instance, patent literature 1 discloses a virtual machine system configured in such a manner that request contents from a number of operating systems are managed to thereby reduce the electric power consumption.
More specifically, the virtual machine system disclosed in patent literature 1 is a virtual machine system for executing a number of operating systems. The virtual machine system includes storage means for storing execution information including execution states of hardware devices in the operating systems. The virtual machine system further includes request receiving means for receiving at least one of a power-on request and a power-off request with respect to a hardware device. The virtual machine system further includes power source switching control means configured to control execution of processes relating to requests based on the execution information. The power source switching control means is configured in such a manner that a process for a power-on request or a process for a power-off request is not executed during use of a certain hardware device by the other operating system, in the case where a target operating system issues a power-on request and a power-off request to the hardware device.
However, in the virtual machine system disclosed in patent literature 1, a virtual machine control device capable of managing each of the operating systems performs electric power saving control, while managing an execution state of each of the operating systems with respect to a hardware device, and power on-off requests.
In other words, in the configuration of patent literature 1, it is necessary to provide an electric power saving function in the virtual machine control device, in addition to the electric power saving function in the operating systems.